Order Parameter Structure in Thin Films and Disordered Superfluid 3He

该项目将研究无序对超流3 He的影响，3 He是一类重要的量子流体，包括超导体，重费米子超导体和高温超导体。 这些非常规系统是由处于BCS态的费米子对形成的。 它们都具有超越规范对称性的自发破缺这一重要的共同特征。 因此，它们对杂质效应特别敏感，如果要理解这些系统的基本行为，如果要实现其应用的潜力，就必须对其进行研究。 拟议的研究将带来精确的实验工具，横向高频声学，热容和薄膜方法，可用于气凝胶玻璃中的3 He，以确定序参数抑制和低位激发的密度，并与最近的理论预测进行比较。 这些结果将对非常规超导体、玻色-爱因斯坦凝聚和奇异涡旋物质产生广泛的影响。 研究生参与这项工作将为他们提供与基础研究和工业利益相关的技术培训。 关于声学的本科项目将为课堂之外的学习提供补充机会。该项目将研究无序对超流3 He的影响，3 He是包括高温超导体在内的一类重要的量子流体。 这些系统表现出高度的脆弱性，也就是说，它们对所有形式的缺陷和杂质都非常敏感。 无序的调查是至关重要的，他们的基本理解和实现其潜在的应用。 3 He是研究此类效应的理想选择，因为它的纯态已被充分理解。 这与许多超导体形成对比，超导体具有难以控制的物理和化学复杂性。 拟议的研究包括热力学和声学测量，同时系统地控制高度多孔二氧化硅气凝胶引入的无序。 这项工作是相关的理论模型中子星星的问题，夸克库珀对，和异国情调的涡旋状态，其中3 He往往是一个参考点。 本科生将参与使用相位调制声学和第二声音传播的拟议研究。 在磁共振，低温方法和高频声学的技术复杂领域的研究生培训将为他们提供一系列对我们社会具有重大潜在影响的专业职业机会。

This project will investigate the influence of disorder on superfluid 3He, one of an important class of quantum fluids that includes ruthenate superconductors, heavy fermion superconductors, and high temperature superconductors. These unconventional systems are formed from pairs of fermions in BCS states. They all have the common important characteristic of spontaneously broken symmetries beyond gauge symmetry. As such they are particularly sensitive to impurity effects, which must be investigated if the underlying behavior of these systems is to be understood and if the potential for their application is to be realized. The proposed research will bring precise experimental tools, transverse high frequency acoustics, heat capacity, and thin film methods, that are available for 3He in aerogel glass, to determine order parameter suppression and the density of low-lying excitations and to compare with recent theoretical predictions for gapless superconductivity. The results will have broad implications for unconventional superconductors, Bose-Einstein condensation, and exotic vortex matter. The participation of graduate students in this work will provide them with technical training relevant to basic research and industrial interests. Undergraduate projects on acoustics will give opportunities for learning complementary to, but outside, the classroom. This project will investigate the influence of disorder on superfluid 3He, one of an important class of quantum fluids that includes high temperature superconductors. These systems exhibit a high degree of fragility, that is, they have extreme sensitivity to all forms of imperfection and impurities. Investigation of disorder is crucial to their basic understanding and to a realization of their potential for applications. 3He is an ideal choice to study such effects since its pure state is well understood. This is in contrast to many superconductors which have physical and chemical complexity that is difficult to control. The proposed research includes, thermodynamic and acoustic measurements while systematically controlling disorder introduced with highly porous silica aerogel. The work is relevant to theoretical models for neutron star matter, quark Cooper pairs, and exotic vortex states for which 3He is often a reference point. Undergraduate students will participate in the proposed research using phase modulation acoustics and second sound propagation. Training of graduate students in the technically sophisticated areas of magnetic resonance, low-temperature methods, and high frequency acoustics will prepare them for a range of professional career opportunities with a significant potential impact to our society.